The phenomena of primary visual perception, as carried out by the photoreceptor cell of the retina, is supported by a vast number of accessory functions such as regulatory processes controlled by levels of cyclic nucleotides, transport processes for molecular renewal, and the regulated processes of transcription and translation. The molecular components which carry out these many accessory functions are, for the most part, unidentified and uncharacterized. This proposal outlines methods for a) mapping these macromolecules by electrophoretic techniques, to provide a marker system to characterize the host of proteins present in each subcellular part; b) isolation and purification of a set of regulatory enzymes involved in cGMP metabolism; and c) the in vitro reconstitution of these proteins to form a model system in which the molecular mechanisms of cyclic nucleotide control may be examined in detail. A second set of studies outlines methods for purification of the mRNA for the molecular photoreceptor rhodopsin from the retina and the study of the in vitro translation products of this message. Experiments will be carried out with normal retinal tissue and cell lines derived from retinoblastomas. The direct application of this research is to provide information at the molecular level which may elucidate the biochemical defects implicated in photoreceptor retinal degenerations or photoreceptor retinoblastomas, both of which are inherited retinal birth defects.